Re: Activation points and callout modes

[Forwarded email from Alex, who currently has problems posting to the 
OPES list].

> ------------------------------------------------------------------------
> 
> Subject:
> Re: Activation points and callout modes
> From:
> "Alex Rousskov" <[email protected]>
> Date:
> Sun, 20 Feb 2005 22:48:01 -0700
> To:
> "Martin Stecher" <[email protected]>, [email protected]
> 
> To:
> "Martin Stecher" <[email protected]>, [email protected]
> 
> 
> On Fri, 2005/01/28 (MST), <[email protected]> wrote:
> 
>>   1. Receiving email
>>      Do a SMTP dialog with the peer, receiving email from it,
>>      usually storing the emails in a queue and maybe sending on later
>>  2. Stored email in queue
>>      Operate on an email that has been received earlier. Their is
>>      no current SMTP dialog going on
>>  3. Sending email
>>      Do a SMTP dialog with a peer, sending email to it.
>>  4. Proxy (receive and forward)
>>      Having two SMTP dialogs at the same time. Mostly forwarding
>>      commands and replies; often no own email queue
> 
> 
> FWIW, it looks to me that, *from OPES point of view*, 1 and 3 are  
> essentially the same, and 4 is essentially a combination (or concurrent  
> application) of 1 and 3. Number 2 is out of OPES/SMTP scope; it could 
> be  in some future OPES/MIME scope.
> 
> This makes the situation essentially equivalent to the one we have in  
> OPES/HTTP: The difference between 1, 3, and possibly 4 can be 
> accomodated  by two or possibly three OCP profiles that share most of 
> their properties.
> 
>> In addition to that there are four modes
>>
>>   A. SMTP command modification
>>      The command is modified by the callout server
>>  B. SMTP command satisfaction
>>      Callout server responds with a SMTP reply (usually an error
>>      message).
>>  C. SMTP reply modification
>>      The SMTP reply is modified by the callout server
>>  D. Email message body modification
>>
>> Re C: SMTP reply modification seems to make sense for
>>     - reply logging (so no real modification)
>>     - At activation point 4, when commands and replies are proxied
> 
> 
> I do not yet understand why SMTP reply modification is essential for 
> AP#4  if it is not essential for other APs. Did I miss an example posted 
> earlier  (I did go through all the messages on the list)?
> 
>> Re D: When part of OCP/SMTP (not OCP/MIME or alike) this can be
>> seen as command modification, i.e. it falls back to mode A.
> 
> 
> Yes, at this level of abstraction there is no difference.
> 
> Alex.